Oil pressure control device

Abstract

An oil pressure control device includes a plurality of solenoid valves, and a foreign matter discharge unit which carries out foreign matter discharge treatment for a treatment period composed of a first period T 1 in which a current smaller than a predetermined value is supplied to one of the solenoid valves and a second period T 2 in which a current equal to or larger than the predetermined value is supplied to the one of the solenoid valves, and makes timings for varying the current values different from one another so as to start supplying a current equal to or larger than the predetermined current value to another one of the solenoid valves at the beginning of the first period T 1 , and to start supplying a current smaller than the predetermined value to the another one of the solenoid valves at the beginning of the second period T 2.

1. An oil pressure control device comprising:
 a first solenoid valve and a second solenoid valve, having pressure regulating valves for regulating pressures of a working fluid supplied thereto in accordance with displacement strokes of valve bodies and outputting the regulated pressures respectively and electromagnetic drive portions for displacing the valve bodies of the pressure regulating valves with forces corresponding to supplied currents respectively; 
 a first control valve that is actuated using a working fluid pressure output from the first solenoid valve as a pilot pressure, and that regulates a pressure of the supplied working fluid in accordance with a supply pressure of the working fluid and the pilot pressure from the first solenoid valve; 
 a second control valve that has input thereto the working fluid pressure regulated by the first control valve as an original pressure and is actuated using a working fluid pressure output from the second solenoid valve as a pilot pressure, and that regulates the pressure of the working fluid at the original pressure in accordance with the pilot pressure from the second solenoid valve and outputting the regulated pressure; and 
 a foreign matter discharge unit that carries out a foreign matter discharge treatment for the first solenoid valve and the second solenoid valve by varying current values of currents supplied to the first solenoid valve and the second solenoid valve respectively in an increasing direction or a decreasing direction and displacing the valve bodies of the respective solenoid valves in a reciprocating manner, wherein: 
 the foreign matter discharge unit carries out the foreign matter discharge treatment for a treatment period composed of a first period in which a current smaller than a predetermined current value is supplied to one of the first solenoid valve and the second solenoid valve and a second period in which a current equal to or larger than the predetermined current value is supplied to the one of the solenoid valves; and 
 the foreign matter discharge unit starts supplying a current equal to or larger than the predetermined current value to the other of the first solenoid valve and the second solenoid valve at a beginning of or during the first period, and starts supplying a current smaller than the predetermined current value to the other of the solenoid valves at a beginning of or during the second period. 
 
     
     
       2. The oil pressure control device according to  claim 1 , wherein:
 the first solenoid valve and the second solenoid valve are each designed as a normally open-type solenoid valve for maximizing an output pressure of the working fluid when a minimum current value within a variation range of the current value is obtained; and 
 the foreign matter discharge unit sets, when the current supplied to one of the first solenoid valve and the second solenoid valve assumes a maximum current value, the current supplied to the other of the first solenoid valve and the second solenoid valve to the minimum current value, sets the current supplied to the one of the solenoid valves to an intermediate current value smaller than the maximum current value and larger than the minimum current value when the current supplied to the other of the solenoid valves assumes the maximum current value, and sets the current supplied to the one of the solenoid valves to the minimum current value when the current supplied to the other of the solenoid valves assumes the intermediate current value. 
 
     
     
       3. The oil pressure control device according to  claim 2 , wherein the foreign matter discharge unit changes the current supplied to each of the first solenoid valve and the second solenoid valve from the minimum current value to the maximum current value within the variation range of the current value in starting to supply the current equal to or larger than the predetermined current value to the one of the solenoid valves. 
     
     
       4. The oil pressure control device according to  claim 1 , wherein the first solenoid valve and the second solenoid valve are each designed as a linear solenoid valve for translating a corresponding one of the valve bodies, which assumes a spool-like shape, in accordance with a thrust force from a corresponding one of the electromagnetic drive portions. 
     
     
       5. The oil pressure control device according to  claim 1 , wherein the second control valve has an output port for the working fluid at the regulated pressure, and the output port is connected to an oil pressure introduction port of an actuator constituting part of a vehicular continuously variable transmission. 
     
     
       6. The oil pressure control device according to  claim 1 , wherein the first control valve and the second control valve have an output pressure based on the pilot pressure from the first solenoid valve and an output pressure based on the pilot pressure from the second solenoid valve respectively, and the output pressure of the first control valve decreases when the output pressure of the second control valve increases, and increases when the output pressure of the second control valve decreases, in the treatment period in which the foreign matter discharge treatment is carried out. 
     
     
       7. The oil pressure control device according to  claim 1 , wherein:
 the first solenoid valve and the second solenoid valve are equipped with feedback pressure chambers for introducing output pressures from output ports thereof respectively; and 
 each of the feedback pressure chambers has two pressure receiving faces opposed to each other in an axial direction of a corresponding one of the solenoid valves, and the one of the pressure receiving faces which receives a pressure identical in direction to an urging force from a corresponding one of the electromagnetic drive portions has a larger area than the one of the pressure receiving faces which receives a pressure opposite in direction to the urging force. 
 
     
     
       8. The oil pressure control device according to  claim 1 , wherein the predetermined current value is a value corresponding to a control target oil pressure immediately after or before the foreign matter discharge treatment. 
     
     
       9. The oil pressure control device according to  claim 1 , wherein the predetermined current value is a value corresponding to a control target oil pressure immediately after or before the foreign matter discharge treatment. 
     
     
       10. A control method in an oil pressure control device equipped with a first solenoid valve, a second solenoid valve, a first control valve and a second control valve, the method comprising:
 making determinations on states of the first solenoid valve and the second solenoid valve; 
 determining whether or not a predetermined foreign matter discharge condition is fulfilled; and 
 starting to supply, at a beginning of or during a first period in which a current smaller than a predetermined current value is supplied to one of the first solenoid valve and the second solenoid valve, a current equal to or larger than the predetermined current value to the other of the first solenoid valve and the second solenoid valve, and starting to supply a current smaller than the predetermined current value to the other of the solenoid valves at a beginning of or during a second period in which a current equal to or larger than the predetermined current value is supplied to the one of the solenoid valves, when the foreign matter discharge condition is fulfilled, 
 wherein the first control valve is actuated using a working fluid pressure output from the first solenoid valve as a pilot pressure, and regulates a pressure of the supplied working fluid in accordance with a supply pressure of the working fluid and the pilot pressure from the first solenoid valve, and 
 the second control valve has input thereto the working fluid pressure regulated by the first control valve as an original pressure and is actuated using a working fluid pressure output from the second solenoid valve as a pilot pressure, and regulates the pressure of the working fluid at the original pressure in accordance with the pilot pressure from the second solenoid valve and outputs the regulated pressure. 
 
     
     
       11. The control method according to  claim 10 , wherein the predetermined foreign matter discharge condition is a condition that operational malfunctions of the first solenoid valve and the second solenoid valve are estimated from supplied currents and a state of response in an oil pressure circuit to the states of the solenoid valves in a certain period prior to start of neutral control.